NM_000038.6:c.288T>A

Variant names:

• chr5-112767256-T-A
• rs376213437
• NM_000038.6:c.288T>A

Variant summary

Our verdict is Pathogenic. Variant got 19 ACMG points: 19P and 0B. PVS1 PM2 PP3 PP5_Very_Strong

The NM_000038.6(APC):​c.288T>A​(p.Tyr96*) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,852 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: APC NM_000038.6 stop_gained
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:8
• Conservation: PhyloP100: -0.648

Genes affected

APC (HGNC:583): (APC regulator of WNT signaling pathway) This gene encodes a tumor suppressor protein that acts as an antagonist of the Wnt signaling pathway. It is also involved in other processes including cell migration and adhesion, transcriptional activation, and apoptosis. Defects in this gene cause familial adenomatous polyposis (FAP), an autosomal dominant pre-malignant disease that usually progresses to malignancy. Mutations in the APC gene have been found to occur in most colorectal cancers, where disease-associated mutations tend to be clustered in a small region designated the mutation cluster region (MCR) and result in a truncated protein product. [provided by RefSeq, Jun 2022]

ACMG classification

Verdict is Pathogenic. Variant got 19 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 5-112767256-T-A is Pathogenic according to our data. Variant chr5-112767256-T-A is described in ClinVar as [Pathogenic]. Clinvar id is 181831.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr5-112767256-T-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
APC	NM_000038.6	c.288T>A	p.Tyr96*	stop_gained	Exon 4 of 16	ENST00000257430.9	NP_000029.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
APC	ENST00000257430.9	c.288T>A	p.Tyr96*	stop_gained	Exon 4 of 16	5	NM_000038.6	ENSP00000257430.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251468 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135912

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000879

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461852 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 727234

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:8

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Familial adenomatous polyposis 1 Pathogenic:3

Nov 03, 2021

Baylor Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Apr 25, 2023

Myriad Genetics, Inc.

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is considered pathogenic. This variant creates a termination codon and is predicted to result in premature protein truncation. -

Feb 11, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Tyr96*) in the APC gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in APC are known to be pathogenic (PMID: 17963004, 20685668). This variant is present in population databases (rs376213437, gnomAD 0.0009%). This premature translational stop signal has been observed in individual(s) with attenuated familial adenomatous polyposis (AFAP) and colon polyps (PMID: 24549056, 26681312). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 181831). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -

not provided Pathogenic:3

-

Department of Pathology and Laboratory Medicine, Sinai Health System

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

The APC p.Tyr96X variant was identified once in the literature in a cohort of individuals with familial adenomatous polyposis (Lagarde 2010). The total number of individuals in the study was not provided however, and the variant in this study had a different nucleotide change (c.288T>G) which resulted in the same change at protein level as the variant identified by our lab. The p.Tyr96X variant leads to a premature stop codon at position 96. This alteration would typically be predicted to result in a truncated or absent protein and loss of function; however, one study has demonstrated that for APC mutations closer to the 5’ terminus, an internal ribosome entry site is utilized to initiate translation at codon 184, resulting in a partially functional N-terminally truncated protein, which results in an attenuated phenotype (Heppner Goss 2002). In summary, based on the above information, this variant is classified as pathogenic. -

Nov 05, 2021

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Nonsense variant predicted to result in protein truncation or nonsense mediated decay in a gene for which loss-of-function is a known mechanism of disease; Not observed at significant frequency in large population cohorts (Lek et al., 2016); This variant is associated with the following publications: (PMID: 23159591, 26681312, 20685668, 30720243, 24549056) -

Apr 11, 2018

Quest Diagnostics Nichols Institute San Juan Capistrano

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Familial multiple polyposis syndrome Pathogenic:1

Jul 02, 2023

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: APC c.288T>A (p.Tyr96X) results in a premature termination codon, predicted to cause a truncation of the encoded protein or absence of the protein due to nonsense mediated decay, which are commonly known mechanisms for disease. The variant allele was found at a frequency of 4e-06 in 251468 control chromosomes. c.288T>A has been reported in the literature in multiple individuals affected with Familial Adenomatous Polyposis (example, Ibrahim_2014, Park_2022, Susswein_2016). These data indicate that the variant is very likely to be associated with disease. The following publications have been ascertained in the context of this evaluation (PMID: 24549056, 34897210, 26681312). Four submitters have cited clinical-significance assessments for this variant to ClinVar after 2014. All submitters classified the variant as pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -

Hereditary cancer-predisposing syndrome Pathogenic:1

Jan 04, 2023

Ambry Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.Y96* pathogenic mutation (also known as c.288T>A), located in coding exon 3 of the APC gene, results from a T to A substitution at nucleotide position 288. This changes the amino acid from a tyrosine to a stop codon within coding exon 3. This alteration has been identified in several familial adenomatous polyposis (FAP) and colorectal cancer (CRC) patients (Ambry internal data; Ibrahim A et al. Eur. J. Hum. Genet., 2014 Nov;22:1330-3; Susswein LR et al. Genet. Med., 2016 Aug;18:823-32; Lagarde, A et al. J Med Genet 2010 Oct;47(10):721-2; Kim, B et al. BMC Med Genomics 2019 Jul;12(1):103). One publication showed this variant to have attenuated phenotype and to segregate with CRC (Ibrahim A et al. Eur. J. Hum. Genet., 2014 Nov;22:1330-3). In silico splice site analysis predicts that this alteration will result in the creation or strengthening of a novel splice acceptor site. RNA studies have demonstrated that this alteration results in an incomplete splice defect (Ambry internal data). In addition to the clinical data presented in the literature, this alteration is expected to result in loss of function by premature protein truncation or nonsense-mediated mRNA decay. As such, this alteration is interpreted as a disease-causing mutation. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.30
CADD	Pathogenic	34
DANN	Uncertain	0.98
Eigen	Benign	-0.29
Eigen_PC	Benign	-0.62
FATHMM_MKL	Benign	0.26	N
Vest4		0.92, 0.92
GERP RS		-6.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.74		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.74		Position offset: 2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs376213437; hg19: chr5-112102953;